Genotype-environment interactions and genetic parameters in New Zealand Romney sheep : a thesis submitted for the degree of Doctor of Philosophy at Massey University, New Zealand

the permission of the Author.

NEW ZEALAND ROMNEY SHEEP

A t he s i s submi t t ed for the d e g r ee o f Doc t o r o f Philo so phy

a t

Mas s ey Un ive r s i t y New Zealand

SUBHASH CHANDER CHOPRA 1 9 7 8

ABSTRACT

P e r formance records o f 1 , 1 1 3 New Zealand Romney ewe hogge t s f rom two sub f locks maintained on con t rol (CSR) and intens ive (HSR) s tocking r a t e s were ana lysed . The d a t a represented the progeny o f 34 s i res and we re co llected be tween 1 9 6 7 and 1 9 74 inclus ive wh ich covered four

cons e c u t ive two-year s ire p e r iods .

The trai t s inve s t iga t ed were hogge t l ive-we igh t (HLW ) , greasy

f le e c e we ight ( GFW) , c lean woo l we ight per un i t area (WA) , c lean scoured y i e ld (Y) , s taple length ( SL ) , mean f ibre diame t e r (MFD) , s t andard

deviat ion of the f ibre d iame t e r ( S FD ) , qua l i ty numb e r (QN) , cr imp s p e r cent ime ter ( CP C ) , t o t a l cr imp number (TCN ) , character ( CHG ) , t ip p in e s s

(TG) , handle ( HG) , lus t r e (LG ) , greasy co lour (GCG) , scoured colour ( SCG) , discoloured area (DAG ) , cot t ing (CG) , co t t ed area ( CAG ) and s oundness ( SG ) .

S tocking rate had s i g n i f icant e f fect on a l l the t ra i t s exc e p t ing MFD , SFD , TCN and HG . H S R depre s s ed the t r a i t s inve s t iga t ed excep t i ng Y , S FD , QN , CPC , HG , GCG , S CG , CG and CAG . Year e f fe c t s except in DAG

were an impor tant source o f var i a t ion . The inf luence o f b i r t h-rank except on l�W, SFD , CHG and HG was sma l l . S tocking rate x year i n te ract ions except in CPC , TCN , CHG , TG , HG , GCG and CAG were

important . S i re x s tocking rate in terac t ions were s ign i f i can t in HLW ,

MFD , SFD , TCN and GCG only , whe reas s ire x y ear interact ions we re s i gn i f icant in HLW , GFW , HG and SCG .

Sire x s tocking r a t e and s ire ^x year interact ions were included in d i f ferent ways in some formulae for calculat ion of he r i t ab i l i t y e s t ima t e s . The s e e s t imat e s were c a l culated f rom p a t e rnal half-sib analy s e s in C S R ,

HSR and combined dat a . The various e s t imat e s f o r t h e d i f fe rent t ra i t s we re in the following ranges : -

H LW 0 . 2 1 - 0 . 7 2 , GFW 0 . 3 8 - 0 . 6 1 , WA 0 . 3 1 - 0 . 4 9 ,

y 0 . 1 9 ^- 0 . 53 , SL 0 . 54 - 0 . 6 3 , MFD 0 . 34 ^- 0 . 8 7 , S FD 0 . 3 5 - 0 . 6 6 , QN 0 . 4 6 - 0 . 72 , CPC 0 . 48 - 0 . 88 , TCN 0 . 6 5 - 1 . 09 , CHG 0 . 2 4 - 0 . 34 , TG 0 . 1 3 - 0 . 2 7 , HG 0 . 2 3 - 0 . 6 6 , LG 0 . 32 - 0 . 4 2 , GCG 0 . 2 2 - 0 . 44 , SCG 0 . 1 0 ^--' 0 . 39 , DAG 0 . 04 0 . 2 1 , CG 0 . 1 2 0 . 6 7 , CAG 0 . 1 8 - 0 . 53 , S G 0 . 00 - 0 . 2 2 .

No sign i f i cant d i f fe renc e s bet tveen the es t ima t e s in the two s t o cking rates except in CG and SG were ob served . The relevance o f t h e s e compari sons iS d i s cu s s ed i n t e rms o f s i re x s tocking rate and s ire x year int erac t ions .

Int ra- t r a i t gene t i c correlations be tween the two s tocking rates

were close t o un ity except in HLW (P< 0 . 0 5) ; Y , SFD , GCG , SCG ( 0 . 0 5< P< 0 . 1 ) .

Gene t i c correlat ions be tween t ra i t s we re cal culated by the pa t e rnal

h a l f - sib me thod . The corre lat ion coe f f i c i ents sugge s t that the HLW s e le c t ion resul t s in h i gh e r fleece we igh t , longer s t ap les , bet t e r

f le e ce charac ter , inc reased var iat ion i n f ibre diame t e r , h ighe r qua l i ty number and c r imp ing and mor e lus t re . Selec t ion f o r f leece we igh t would r e s u l t in longer s tap les , less cot t ing and less suscep t Jb i l ity to break

and increased mean f ibre d i ame t e r . Correla ted re spons e s exp e c t ed w i t h s e l e c t ion for f ineness a r e reduced s t aple lengt h , more co t t ing an d l e s s s ound woo l . Select ion ·fo r TCN resul t s in favourab le changes in H LW , GFW , TG , co t t ing , co lour and soundness . Favourab le changes in y ie l d , c r imp ing , d iscoloured area are exp e c t ed following s e l e c t ion for whi tene ss o f a mid s ide sample , whe reas GFW could decl ine .

App l i c a t ion s o f the resul t s are d i s c u s sed with par t i cular re f erence t o the role p layed by s i re x s to cking r a t e and s ire x year i n t e ra c t ions in the gene t ic improvement of charac t e r s of economic imp o r t ance in New Zea land Romney sheep .

AC KNOWLEDGEMENTS

I t is with s p ec ial gra t i t ude that I acknowled ge my s upervisors , Pro f e s sor A.L . Rae and Dr G . A . Wi c kham f o r their immense help , cons t an t encouragement , c on s t ruc t ive c r i t i c i sm and able counsel t hroughout t h e course o f this s t udy and t he p reparat ion o f t h i s t h e s i s .

Gra t e ful acknowledgement is made t o the s t a f f o f Sheep Husb and ry Dep a r t ment and No . l Sheep Farm , Mas sey Un ive r s i t y who were invo lved wi th the c o l l ect ion o f t he d a t a used .

Thanks are due t o Mr R . P . Lewe r , Mr A . B . Pl easan t s and Mr C . J . Dodd f o r the i r as s i s t ance dur ing the period of comput er f ami liarization . They and o t her colleagues and fel l ow s t uden t s h ave p rovided a source o f s t imu l a t ing d i s cuss ion o n many occasions .

S incere t hanks are due t o Mr s A . F . Barton for ski l l f ul ly typ ing t h e manus c r ip t .

I wish t o express my utmo s t app reciat ion and s p e c ia l thanks to my w i f e , Reeta f o r provid ing the i n s p i rat ion . Wi thout her resolu t e support and encouragement t he t a sk may never have been comp le t ed . The a ff e c t ion received f rom t he Chopra and Varma f ami l i e s encouraged me in the a ccomp l ishmen t of t h i s t a s k .

This the sis was made p o s s ib le t h rough the awar d o f a Commonwea l t h S cholarship . The grant o f st udy leave by the Ind i an Coun c i l o f

Agr i cultural Re search i s g r a t e fu l ly acknowledged .

Chap ter

ONE

TWO

THREE

T ABLE O F CONTENT S

ABSTRACT i i

ACKNOHLEDGEMENTS ^V

L I ST OF T ABLES ^X

L I S T OF F I GURES x i i

INTRODUCTION 1

REVIEW CF LITERATURE 4

CLAS S I F I C AT IONS OF GENOTYPE-EN V I RONMENT INTERACTIONS 4

FALCONER ' S CONC EPT OF GENET IC CORRELATIONS BETWEEN PERFORMAN C E IN DIFFERENT ENV IRONMENTS

Exp e r imental ev idence for Fal coner ' s concep t

GENOTYPE- ENVIRONMENT INTERAC T I ONS IN SHEEP Growth charac t e r is t i cs

Car c ass cha r a c ter i s t ics Flee ce charac ter i s t i c s Rep roduc t ive t ra i t s i n ^ewes O t hers

GENETI C PARAMETERS He r itabil ity

Gene t i c corre lations GEN ERA L CONCLUSIONS

SOURCE OF DATA

THE D ATA

1 2 1 3

2 0 2 1 29 3 2 4 1 4 5

4 6 4 fi 6 0 7 8

7 9

8 1

Chap t e r

FOUR

FIVE

TAB LE OF CONTENTS (continued)

STATI STICAL HETHODS

PRESENCE OF INTERACT I ON

ANALY S I S OF VARIANCE

Le ast squares and computing methods Fi t t i ng ^models to ^{the data}

Es t imat i on o f ^mean s quares , variance and covarian c e components

LEAST SQUARES EST IMATES

POOLING OF THE S I RE GRO UP P ERIODS ANALYSES PART ITIONING THE VARIAT ION

VARIANCE CO NPONEN T ESTH1ATES

GENET IC PARANETERS Heritab i l ity

Gene t i c c o r r e la t ions

RESULTS AND DISCUS SION

E S T I NATES OF NON- GENET I C FACTORS , INTERACT I ON S AND VARIANCE C ONPONENTS

Hogge t l ive -we i ght Greasy f l e e c e weight

Clean w o o l we ight p e r un i t a r ea Clean s coured y ie l d

S t aple length

Me an f ib re diame t e r

S t andar d d evia t ion of t h e f i b r e d i ame te r Qua l i ty number

Crimp s per cent ime t e r To t al c r imp numb e r

8 6 86

88 88 9 0 9 6 9 8 9 8 9 9 9 9

1 0 1 1 0 1 1 0 3

1 05

1 0 5 1 1 0 115 1 18 1 20 1 2 1 1 2 4 1 2 5 1 2 7 1 2 8 1 30

Chap t e r

TABL E O F CONTENTS ( c on t inued )

Charac ter grade Tipp iness grade Hand le grade Lus t re grade

Greasy colour grade Scoured colour gr ade D i s coloured area grade Co t t ing grade

Co t t ed area grade Soundne s s grade

HERITABILITY ESTIMATES , INTRA-TRAIT GENETIC CORRELATIONS AND INTERAC TION VARIANCE COMPONENTS

Ho gge t l ive-we i gh t Greasy f leece we i gh t

C l ean woo l we i gh t p e r u n i t area Clean scoured y i e ld

S t aple len g t h

Mean f i bre d i ame t e r

S t andard dev iat ion o f the f i bre diame t e r Qual i ty number

C r imp s p e r cent ime t e r To tal cr imp number Chara c t e r grade Tipp ine s s grade Handle grade Lus tre grade

Greasy c o lour grade Scoured colour grad e D i s coloured area grade Cot t ing grade

Co t t ed area grade Soundne s s grade

INTER-TRAIT GENETI C C ORRELATIONS

1 3 1 1 34 1 3 5 1 3 7 1 3 8 1 4 0 1 4 1 1 4 3 1 4 4 1 4 6

1 4 8 1 5 2 1 5 5 1 5 6 15 7 1 5 8 1 5 9 1 6 1 1 6 2 1 6 3 1 6 4 1 6 5 1 67 1 6 8 1 6 9 1 7 0 1 7 1 1 7 2 1 7 3 1 7 4 1 7 6 1 7 7

C^hapt^er

SIX

TABLE OF CONTENTS (continued)

CONCLUDING DISCUSSION ON PRACTICAL U1PLICATIONS

BIBL10GRAPHY

1 8 5

1 94

Table 1

2

LIST OF TABLES

Some published estimates of heritability of live-weight, wool quantity and quality traits in s heep

Some published estimates of genetic correlations between various characteristics for live-weight, wool quantity and quality in sheep

3 Combined stocking rate analysis. Calculation of reductions in sums of squares and expectations of mean squares

4 Within s tocking rate analysis. Calculation of reductions in sums of squares and expectations of mean squares

5

6 7

8

9

1 0

1 1 1 2 1 3

1 4

1 5

Percentage of total variance attributable to each factor for each variable from the combined stocking rate analysis pooled from the different Sire group periods

Least squares estimates and standard errors of environmental effects for HLW and GFW

Least squares estimates and standard errors of environmental effects for WA and Y

Least squares estimates and standard errors of environmental effects for SL ^{and MFD}

Least squares estimates and standard errors of environmental effects for SFD and QN

Least squares estimates and standard errors of environmental effects for CPC and TCN

Least squares estimates and standard errors of environmental effects for CHG and TG

Least squares estimates and standard errors of environmental effects for HG and LG

Least squares estimates and standard errors of environmental effects for GCG and SCG

Least squares estimates and standard errors of environmental effects for DAG and CG

Least squares estimates and standard errors of environmental effects for CAG and SG

4 8

6 4

9 4

9 5

1 0 6 111 119 1 22 1 2 6 1 2 9 1 3 2 1 3 6 1 3 9 1 4 2 1 4 5

Table 16

17

LIST OF TABLES

(continued)

Heritability estima t es and standard er ro r s of various tra it s obt ained from t he pooled analyses by diffe ren t me thods

Intra-trait genet ic co r relat ions and s t anda rd erro r s of t rait s in two s t o cking rates

18 Gene t ic correlations and s t andard errors among various t raits from the pooled analysis of variance and covariance

14 9

151

178

Fig.

1

2

3

LIST OF FIGURES

Title

Illus t ra t ion of geno t ype (A, B) x environment

(X, Y ) int erac t ions as sugge s t ed by Haldane ( 19 4 6) (aft er McBride, 1958)

Types of heredit y x environment int erac t ion (af t er Dunlop, 19 62)

A classific a t ion of geno t ype x environment interac t ions spec ially de signed for use in farm animals, s t udies (after Pani, 19 71)

5

9

11